Biosorption: a new rise for elemental solid phase extraction methods

Biosorption is a term that usually describes the removal of heavy metals from an aqueous solution through their passive binding to a biomass. Bacteria, yeast, algae and fungi are microorganisms that have been immobilized and employed as sorbents in biosorption processes. The binding characteristics of microorganisms are attributed to functional groups on the surface providing some features to the biosorption process like selectivity, specificity and easy release. These characteristics turn the biosorption into an ideal process to be introduced in solid phase extraction systems for analytical approaches. This review encompasses the research carried out since 2000, focused on the employment of biosorption processes as an analytical tool to improve instrumental analysis. Since aminoacids and peptides as synthetic analogues of natural metallothioneins, proteins present in the cell wall of microorganisms, have been also immobilized on solid supports (controlled pore glass, carbon nanotubes, silica gel polyurethane foam, etc.) and introduced into solid phase extraction systems; a survey attending this issue will be developed as well in this review.     

A review of solid phase extraction: Basic principles and new developments

Summary A review with 178 references on the basic principles and recent developments in the solid phase extraction is presented. New solid phases, chromatographic modes, experimental configurations and off-line and on-line automated devices are discussed.     

Hydrophobic solid phase extraction using n-alkanoic acid-immobilized anion-exchange membranes as adsorbents

In this study, n-alkanoic acids (C7-COOH, C11-COOH, and C17-COOH) were immobilized onto strong basic anion-exchange membranes to form a stationary phase for hydrophobic solid phase extraction (SPE) application. The effects of feed surfactant amount, membrane counter ions, and surfactant chain length were investigated. Immobilized surfactant capacity increased with increasing feed surfactant amount, decreasing chain length, and the existence of OH⁻ counter ions. Moreover, according to TGA analysis, a surfactant bi-layer was formed on the membrane surface. Following successful surfactant immobilization, batch adsorption experiments for doxepin (feed concentration of 0.2 mg/mL) were conducted. The adsorbed doxepin amount increased with the use of longer-chain surfactants, indicating that doxepin adsorption was dominated by hydrophobic interaction with the immobilized surfactant. An optimal desorption performance was achieved using 1 M NaCl in 50% ethanol for both C7-COOH and C11-COOH-immobilized membranes. In the SPE process with one C11-COOH-immobilized membrane, a concentration factor of 2 and complete doxepin recovery was achieved from 10 mL of a 0.1 ppm load.     

Potential sources of background contaminants in solid phase extraction and microextraction

A study to identify the sources of background contamination from SPE, using a C-18 sorbent, and solid-phase microextraction (SPME), using a 70 microm carbowax/divinylbenzene (CW/DVB) fiber, was carried out. To determine the source of contamination, each material used in the procedure was isolated and examined for their contribution. The solid-phase column components examined were: sorbent material and frits, column housings and each solvent used to elute analytes off the column. The components examined in the SPME procedure were: SPME fiber, SPME vials, water (HPLC grade), and salt (sodium chloride) used to increase the ionic strength. The majority of the background contaminants from SPE were found to be from the SPE sorbent material and frits. The class of contaminants extracted during a blank extraction were phthalates and other plasticizers used during the manufacturing process. All had blank levels corresponding to measured concentrations below 2 ng/ mL, except for undecane, which had a concentration of 5.4 ng/mL. The most prevalent contaminants in the SPME blank procedure are 1,9-nonanediol, a mixture of phthalates and highly bis-substituted phenols. All the concentrations were below 2 ng/mL, with the exception of bis (2-ethylhexyl) phthalate, which had concentrations ranging from 5 to 20 ng/mL.     

Investigation of elutions from a surfactant immobilized solid phase extraction sorbent based upon the hydrophobicity of the trapped species

A unique solid phase extraction (SPE) sorbent having a removable “stationary phase” is presented. This removable phase consists of alkyltrimethylammonium surfactant, which is initially immobilized onto hydrophilic strong cation exchange resin. The surfactant chain through hydrophobic interactions extracts hydrophobic analytes in the same manner as conventional bonded alkyl moieties on silica-based non-polar sorbents. For the extraction of very hydrophobic species with conventional sorbents, solvents such methylene chloride and benzene are needed to break strong hydrophobic interactions for efficient elutions. These solvents however are toxic to the analyst and present a significant environmental concern. Using a removable “stationary phase”, hydrophobic interactions need not be broken between the analyte and the sorbent. In the presented approach, the surfactant (“stationary phase”) is removed via ion exchange with exchange ions in very mild aqueous-based and instrument compatible solutions. The analyte, being associated with the surfactant, is also removed in the process. Very efficient elutions of analytes, regardless of hydrophobicity, under mild and more favorable environmental conditions are a direct benefit of having a removable “stationary phase”. Rinse solution parameters explored include exchange cation type and concentration, and alcohol type and concentration. The extraction of three test molecules of varying hydrophobicity, naphthalene, pyrene and benzo(ghi)perylene, is investigated using this sorbent material.     

Silica-titania sol-gel hybrid materials: synthesis, characterization and potential application in solid phase extraction

The biphenilaminepropylsilica and biphenilaminepropylsilicatitania were synthesized by sol-gel method, in two steps: (a) biphenylamine reacts with chloropropyltrimethoxysilane and (b) the product of reaction was polycondensed with tetraethylorthosilicate (TEOS) or TEOS and titanium isopropoxide. The sol-gel materials were characterized using infrared spectroscopy and N₂ adsorption-desorption isotherms and they were employed as sorbents for carcinogenic N-containing compound retention, in aqueous solution, using the SPE technique. The N-containing compounds adsorption was influenced by the titania presence and the sorption process seems to happen in the pores with higher organic density.     

固相萃取-反相高效液相色谱法测定环境水体中卡马西平

建立了固相萃取-反相高效液相色谱法测定水中痕量卡马西平的方法.以C18固相萃取柱对水样固相萃取,再经Agilent ZORBAX Exlipse XDB-C18色谱柱分离,在紫外检测器上检测.考察了洗脱液、流动相比例的影响.确定洗脱液选用甲醇(17+3)溶液,流动相选择甲醇(11+9)溶液.结果线性关系良好(在0.2～...     

钯与对若丹宁偶氮苯甲酸络合物的固相萃取和光度测定

根据新试剂对若丹宁偶氮苯甲酸(RABA)与钯的显色反应及C18固相萃取小柱对显色络合物的固相萃取,建立了一种测定痕量钯的新方法,在pH为2.0～4.0的HCl-邻苯二甲酸氢钾(HCl-KHP)缓冲介质中,在CTMAB存在下,钯与RABA发生反应形成1:1的稳定络合物,该络合物可用C18固相萃取小柱富集,小柱上富集的络合物用乙醇洗脱后用光度法测定,在富集后的测定液中,络合物最大吸收波长为500 nm,摩尔吸光系数ε=1.36×105 L·mol-1·cm-1,Pd2 量在0.1～1.0 μg/mL内符合比尔定律,方法用于催化剂中钯的测定.     

孔雀石绿分子印迹物的制备及其在固相萃取中的应用

以孔雀石绿(MG)为模板分子,甲基丙烯酸(MAA)为功能单体,乙二醇二甲基丙烯酸酯(EGDMA)为交联剂,本体聚合法合成了印迹聚合物(MIP)并对其进行了表征.制备了MIP萃取柱并对上样、淋洗和洗脱条件进行了优化.MIP萃取柱对真实样品中的MG进行了富集并用高效液相色谱测定.两个鱼饲料样品以及一个食用鱼养殖水样中未检出MG,但在两个观赏鱼养殖水样中检出了MG,浓度分别为1.50 ng*mL-1 和0.67 ng*mL-1.     

固相萃取光度法测定烟草中的挥发酚

研究了用Waters Sep-Park-C18固相萃取小柱萃取测定烟草样品中的挥发酚的方法。用自动水蒸汽蒸馏仪蒸馏出烟草样品中的挥发酚，4-氨基安替比林显色，显色产物可用Waters Sep-Park-C18固相萃取小柱萃取，以乙醇洗脱后用分光光度法测定，该方法可用于烟草样品中挥发酚的测定。     

Using on-line solid phase extraction for flow-injection spectrophotometric determination of salbutamol

In the proposed procedure, the determination of salbutamol with Folin-Ciocalteau reagent (FC) using a flow injection analysis technique (FIA) with spectrophotometric detection at 750 nm is described. The lab-made FIA system consisted of a peristaltic pump Gilson Minipulse 3 equipped with Tygon tubes, double 6-port external Vici Valco sample injector and S 2000/SAD500 fiber optic spectrophotometer. It was controlled by a PC with use of originally compiled LabVIEW^®—supported software containing the mathematical library with various statistical functions for off-line data evaluation. Concentration, volume of reagents and flow rate were optimised by a simplex method. The proposed system was used for the direct determination of salbutamol sulphate in the tablets and the human urine without preliminary pre-treatment of the sample. The negative effect of interfering substances (excipients of the tablets and matrix of the urine) is overcome by a solid phase extraction (SPE), when salbutamol is adsorbed on the solid phase in the microcolumn, which is integrated directly into the flow system. Pre-treatment of the sample takes place directly in the flowing stream. The sample throughput without carryover of on-line SPE was 60-80 samples per hour. With the SPE column (Baker—carboxylic acid), salbutamol was determined in the linear range from 1 to 15 μg ml⁻¹ (R.S.D.=1.2%), with detection limit (3σ) 0.1 μg ml⁻¹ and a frequency of 40-60 samples per hour in the water solutions. The salbutamol was determined in the linear range from 2 to 20 μg ml⁻¹ (R.S.D.=1.7%), with detection limit (3σ) 1 μg ml⁻¹ and a frequency of 30 samples per hour in the samples of the human urine.     

Determination of terpenoids in wines by solid phase extraction and gas chromatography

A new method for determination of volatile terpenoids in wine is proposed. An off-line solid phase extraction—gas chromatographic method has been used for the determination. The influence of several extraction variables was studied, including the solid phase employed (C-18 versus divinylbenzene-based), eluting solvent (n-pentane, dichloromethane, ethanol and methanol), volume of eluting solvent (1-4 ml) and drying time (0-20 min). Complete recovery of volatile terpenoids from several kinds of wines was obtained under the optimized conditions.     

Environmental analysis of organic compounds in water using solid phase micro extraction

Solid Phase Micro Extraction (SPME) involves exposing a fused silica fiber coated with stationary phase to a contaminated water sample. The organic analytes become partitioned between the stationary phase and the water and when equilibrium is reached the fiber is removed from the solution and the analytes are thermally desorbed in the injector of a gas chromatograph. The fiber is contained in a syringe to facilitate handling. Factors which affect linear range, limit of detection, and total analysis time are discussed with regard to the development of a method for analysis of volatile compounds in environmental water samples. The sensitivity of the method was determined by the thickness of the film of stationary phase; the equilibration time, however, increased with the film thickness, although it can be minimized by use of a cross-shaped stirrer bar. Increasing the thickness of stationary phase in the analytical column enables the cryofocusing temperature to be increased from ?40 to ?15°C. With an ion trap mass spectrometer, detection limits required by the US Environmental Protection Agency are met for all compounds except chloromethane and chloroethane. The method has been applied to environmental water samples.     

Immobilized polysiloxanes as stationary phases for high-performance liquid chromatography and solid phase extraction

Polysiloxanes immobilized onto the surfaces of porous silica particles have proven to be good stationary phases for the separation of multiresidues of pesticides and their metabolic/degradation products by reversed-phase high-performance liquid chromatography (RP-HPLC). Similar materials have proven effective for pre-concentration and clean-up procedures using solid phase extraction. The present paper describes the preparation and some applications of several of these packing materials.     

尼泊金乙酯分子印迹固相萃取小柱的研制及应用

研制了一种对尼泊金乙酯具有特异性识别性能的分子印迹固相萃取小柱。用本体聚合法制备尼泊金乙酯分子印迹聚合物,通过静态平衡吸附实验及固相萃取实验表征其固相萃取性能,并结合UV法对滴眼液中的尼泊金乙酯进行测定。结果显示,尼泊金乙酯模板聚合物的吸附能力强于空白聚合物;印迹固相萃取柱对尼泊金乙酯标准溶液(0.04mmol/L)一...     

液液提取-固相萃取-气相色谱法测定牛肉中蝇毒磷残留量的研究

建立了液液提取-固相萃取-气相色谱火焰光度法(LLE-SPE-GC-FPD)测定牛肉中蝇毒磷的残留量.优化了气相色谱分离条件,研究了样品基质对蝇毒磷测定的影响,考察了Florisil固相萃取小柱和ODS固相萃取小柱的萃取效果,并选择乙酸乙酯为洗脱剂,考察了液-液提取和固相萃取的回收率.将该方法用于牛肉中蝇毒磷的测定,其检出限为0.02 μg/mL,回收率高于83%,相对标准偏差13.7%.使用气相色谱质谱仪(GC-MS)对样品中的蝇毒磷进行定性分析,其特征离子和相对丰度为362(100)、226(55)和210(40).     

Analytical applications of admicelle and hemimicelle solid phase extraction of organic analytes

A current literature review, consisting of 42 publications, is provided on the topic of using admicelle/hemimicelle formations on solids for the analytical scale preconcentration of a variety of organic analytes.     

Determination of triazine herbicides using membrane-protected carbon nanotubes solid phase membrane tip extraction prior to micro-liquid chromatography

A novel microextraction technique termed solid phase membrane tip extraction (SPMTE) was developed. Selected triazine herbicides were employed as model compounds to evaluate the extraction performance and multiwall carbon nanotubes (MWCNTs) were used as the adsorbent enclosed in SPMTE device. The SPMTE procedure was performed in semi-automated dynamic mode and several important extraction parameters were comprehensively optimized. Under the optimum extraction conditions, the method showed good linearity in the range of 1–100 μg/L, acceptable reproducibility (RSD 6–8%, n = 5), low limits of detection (0.2–0.5 μg/L), and satisfactory relative recoveries (95–101%). The SPMTE device could be regenerated and reused up to 15 analyses with no analyte carry-over effects observed. Comparison was made with commercially available solid phase extraction-molecular imprinted polymer cartridge (SPE-MIP) for triazine herbicides as the reference method. The new developed method showed comparable or even better results against reference method and is a simple, feasible, and cost effective microextraction technique.